Aspirated relief valve for a turbocharging system

ABSTRACT

A valve assembly is disclosed, and includes an evacuator and a relief valve. The evacuator includes a suction port that selectively applies a vacuum. The relief valve has an open position and a closed position, and includes an inlet, an outlet, a piston that translates within a chamber, and a pressurized chamber. The piston includes a first end and a second end. The pressurized chamber is fluidly connected to the suction port of the evacuator, and is defined in part by the first end of the piston. The piston translates within the pressurized chamber towards the open position if vacuum is applied to the pressurized chamber.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/025,548, filed on Jul. 17, 2014.

TECHNICAL FIELD

The present invention relates generally to a relief valve, where anevacuator is used to provide a vacuum to actuate the relief valve intoan open position.

BACKGROUND

Internal combustion engines may be used in a variety of applicationssuch as, for example, passenger and industrial vehicles, marine,stationary and aerospace applications. There are generally two dominantignition cycles, which are commonly referred to as gas and dieselcycles, or more formally as spark ignited (SI) and compression ignition(CI) cycles, respectively.

Exhaust-driven turbochargers may be used to improve the power output andoverall efficiency of an internal combustion engine. Specifically,exhaust gas energy may be used to drive a turbine. The turbochargerincludes a compressor and a turbine, where the compressor is mounted ona shaft of the turbocharger, opposite the turbine. The turbine convertsengine exhaust gas into mechanical energy, which is used to drive thecompressor. The compressor draws in and compresses air. The compressedair is then directed to an intake manifold of the internal combustionengine.

A relief valve, such as a compressor discharge valve or a blow-offvalve, may be mounted on an intake pipe located downstream of theturbocharger before a throttle. Specifically, a compressor dischargevalve may be used to vent compressed air back into an inlet of thecompressor. A blow-off valve is similar to a compressor recirculationvalve, but vents to the atmosphere rather than back to the inlet of thecompressor. The relief valve may be used to alleviate a sudden surge orspike in pressure that may occur when the throttle closes (i.e., when anoperator suddenly lifts his or her foot off of the gas pedal and thethrottle closes).

Air compression systems have been used on semi-trucks and other types ofcommercial vehicles in order to power air brakes. The air compressionsystem may include an air compressor that is used to supply compressedair to a storage tank. The air compressor may be powered by a crankshaftpulley, or by timing gears of the internal combustion engine. Thecompressed air in the storage tank may be used for the air brakes. Inaddition to the air brakes, the compressed air may also be used toactuate the relief valve (i.e., the compressor discharge or blow-offvalve). Specifically, a vacuum pump may allow the compressed air in thestorage tank to selectively flow to the relief valve. The vacuum pumpmay be driven by an electric motor, or by the crankshaft or otherrotatable shaft of the internal combustion engine. However, the vacuumpump may add significant cost and complexity to the system. Accordingly,there exists a need in the art for a simpler, cost-effective approach toactuate a relief valve in a turbocharger system, especially insemi-trucks and other types of commercial vehicles.

SUMMARY

The disclosed valve assembly includes a relief valve and an evacuator.The evacuator may be used to create a vacuum within a pressurizedchamber of the relief valve. The vacuum created by the evacuator is arelatively simple and low-cost approach to actuate the relief valve froma closed position and into an open position.

In one aspect, the disclosed valve assembly includes an evacuator and arelief valve. The evacuator includes a suction port that selectivelyapplies a vacuum. The relief valve has at least an open position and aclosed position, and includes an inlet, an outlet, a piston thattranslates within a chamber, and a pressurized chamber. The pistonincludes a first end and a second end. The pressurized chamber isfluidly connected to the suction port of the evacuator, and is definedin part by the first end of the piston. The piston translates within thechamber towards the open position if vacuum is applied to thepressurized chamber.

In another aspect, a system including an exhaust-driven turbo charger isdisclosed and includes a storage tank containing compressed air, acontrol valve that is selectively opened to allow for the compressed airwithin the storage tank to flow therethrough, an evacuator and reliefvalve. The evacuator is fluidly connected to the control valve and acompressor inlet of the exhaust-driven turbo charger. The evacuatorincludes a suction port that applies a vacuum if the control valve isopened. The relief valve has at least an open position and a closedposition. The relief valve is fluidly connected to the evacuator. Therelief valve is actuated into the open position if the vacuum is appliedby the evacuator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram including flow paths and flow directions of oneembodiment of an internal combustion engine turbo system that includes arelief valve and an evacuator.

FIG. 2 is a diagram of the relief valve and evacuator shown in FIG. 1,where the relief valve is in a closed position.

FIG. 3 is a diagram of the relief valve and evacuator shown in FIG. 1,where the relief valve is in an open position.

FIG. 4 is a diagram of the evacuator shown in FIG. 1.

FIG. 5 is a diagram of an alternative embodiment of a variable reliefvalve and evacuator shown in FIG. 1.

FIGS. 6 and 7 are an illustration of one embodiment of a variable reliefvalve in a closed position.

FIG. 8 is an illustration of the variable relief valve shown in FIG. 6in a partially opened position.

FIG. 9 is an illustration of the variable relief valve shown in FIG. 6in an open position.

DETAILED DESCRIPTION

The following detailed description will illustrate the generalprinciples of the invention, examples of which are additionallyillustrated in the accompanying drawings. In the drawings, likereference numbers indicate identical or functionally similar elements.

Referring now to FIG. 1, an exemplary schematic diagram of a turbosystem 10 for an internal combustion engine 12 is illustrated. In oneembodiment, the internal combustion engine 12 is a compression ignition(“CI”) or diesel engine of a vehicle 1, however it is to be understoodthat other types of engines such as spark ignited (SI) or gas enginesmay be used as well. The turbo system 10 may include an exhaust-driventurbo charger (“EDT”) 20 having a turbine section 22 and compressorsection 24, a turbine bypass valve or wastegate 26, and a relief valve30. An exhaust housing 18 of the EDT 20 contains a turbine wheel 32. Aturbine wheel 32 harnesses and converts exhaust energy into mechanicalwork through a common shaft 34 to turn a compressor wheel 35. Thecompressor wheel 35 ingests, compresses and feeds air at elevatedoperating pressures into an intake manifold 36 of the internalcombustion engine 12.

The wastegate 26 is a control valve used to meter an exhaust volume 37exiting an exhaust manifold 40 of the internal combustion engine 12, andcontrols the amount of energy available to power the turbine wheel 32.The wastegate 26 works by opening a valve (not shown) connected to abypass pipe 42. Opening the valve of the wastegate 26 allows for exhaustto flow away from the turbine wheel 32. Thus, the wastegate 26 may havedirect control over the speed of the EDT 20 and the resultant operatingpressure of the intake manifold 36 of the internal combustion engine 12.The wastegate 26 may have any number of embodiments, including theembodiments disclosed in Applicant's U.S. Pat. No. 8,469,333, which isincorporated by reference herein in its entirety.

Operation of the EDT 20 may now be explained. It is to be appreciatedthat operating pressures exist in an EDT compressor inlet 50, the intakemanifold 36 of the internal combustion engine 12 and an intake manifoldpipe 52, the exhaust manifold 40 of the internal combustion engine 12and an intake manifold pipe 54, an exhaust inlet 58 of the EDT 20, andan exhaust outlet 59 of the EDT 20. Specifically, the EDT compressorinlet 50 may be defined as the passageway from an air intake system 60to an inlet 64 of the compressor section 24. The intake manifold 36 ofthe internal combustion engine 12 may be defined as the passage betweenan EDT compressor discharge 66 and one or more intake valves 68 of theinternal combustion engine 12. The exhaust manifold 40 of the internalcombustion engine 12 may be defined as the passage between one or moreexhaust valves 70 and the exhaust inlet 58 of the EDT. The exhaust maybe any passageway located after the exhaust outlet 59 of the EDT 20.

A storage tank 86 may be used to store high pressure or compressed air.A secondary air compressor (not illustrated) may be used to supply thecompressed air located in the storage tank 86. In one embodiment, thecompressed air may be used for power air brakes (not illustrated) on thevehicle 1. In addition to the air brakes, the compressed air stored inthe air tank 86 may also be used for supplying compressed air to anevacuator 88, which is described in greater detail below.

The relief valve 30 may be a regulating valve located in the intakemanifold pipe 52 between the compressor discharge 66 of the compressorsection 24 of the EDT 20 and the intake manifold 36 of the internalcombustion engine 12. In the embodiment as shown in FIG. 1, the reliefvalve 30 is a compressor recirculation valve that is fluidly connectedto and vents compressed air back into the EDT compressor inlet 50.However, it should be noted that in another embodiment, the turbo system10 may utilize a blow-off valve as well. A blow-off valve is similar toa compressor recirculation valve, but vents to the atmosphere ratherthan back to the compressor inlet of an EDT. An on/off or control valve38 may be fluidly connected upstream of the evacuator 88, and is used toselectively allow the compressed air within the storage tank 86 to flowthrough the evacuator 88. In one embodiment, the control valve 38 may bea solenoid valve. A muffler or noise attenuator 89 may be locateddownstream of the evacuator 88, between the control valve 38 and the EDTcompressor inlet 50.

A high-pressure pipe 90 may be used to fluidly connect the storage tank86 to the evacuator 88. The evacuator 88 may be located between thestorage tank 86 and the EDT compressor inlet 50. The evacuator 88 may bein fluid communication with the control valve 38, the relief valve 30,and the EDT compressor inlet 50. The evacuator 88 may be a relativelysimple, cost-effective approach for creating a vacuum in the reliefvalve 30. The vacuum created by the evacuator 88 may be used to actuatethe relief valve 30 into an open position, which is described in greaterdetail below. In an alternative embodiment, the evacuator 88 may belocated between the storage tank and atmosphere.

In the exemplary embodiment as shown in FIG. 1, the relief valve 30 maybe used with a throttle plate 80. At any given operating range of theinternal combustion engine 12, the shaft 34 of the EDT 20 may bespinning up to 200,000 revolutions per minute (RPM). A sudden closing ofthe throttle 80 does not immediately decelerate the RPM of the EDT 20.Therefore, this closing creates a sudden increase in pressure in thepassages between the closed throttle 80 and EDT compressor section 24(i.e., the intake manifold pipe 52). The relief valve 30 may be used torelieve or bypass the compressor output pressure that is greater thanwhat is required due to the sudden closing of the throttle 80.

When the relief valve 30 is opened the EDT 20 may spin freely, therebyconserving the inertia of the EDT 20. If the relief valve 30 wasomitted, the EDT 20 would stall or stop once the throttle 80 is closed.This stalling or stopping may adversely affect EDT life and throttleresponse. Those skilled in the art will appreciate that the EDT 20should be spinning and ready to produce boost as soon as the throttleplate 80 is opened. The relief valve 30 may decrease turbo lag byallowing the EDT 20 to spin up to speed (i.e., spool up) withoutcompressor load, as there is no back pressure present once the reliefvalve 30 is opened.

In one embodiment, the relief valve 30 is a variable relief valve. Thevariable relief valve is illustrated in FIG. 5, and is also described ingreater detail below. A variable relief valve may allow for just theamount of bypass required to substantially prevent compressor surge.Compressor surge may be defined as when the air pressure after thecompressor wheel 35 is actually higher than what the compressor wheel 35is capable of maintaining. This condition causes the airflow in thecompressor wheel 35 to back up, build pressure, or stall. Thus,compressor surge is noisy, affects EDT life, and may reduce theperformance of the turbo system 10.

FIGS. 2-3 are a schematic diagram of the relief valve 30, the controlvalve 38, the evacuator 88, the storage tank 86, the noise attenuator89, and a controller 92. In one embodiment, the controller 92 may be anengine or a powertrain control module. The engine controller may be usedto provide control of one or more functions of the internal combustionengine 12 (FIG. 1). The controller 92 may be in signal communicationwith the control valve 38. The controller 92 may refer to an applicationspecific integrated circuit (ASIC), an electronic circuit, a processor(shared, dedicated, or group) and memory that executes one or moresoftware or firmware programs, a combinational logic circuit, or othersuitable components that provide the described functionality.

The relief valve 30 may include a valve body 100 that defines an inletport 102, an outlet port 104, and a pressurized chamber 106. In thenon-limiting embodiment as shown in FIGS. 2-3, the inlet port 102 of therelief valve 30 is fluidly connected with the EDT compressor discharge66 (FIG. 1) and the outlet port 104 is fluidly connected with EDTcompressor inlet 50 (FIG. 1). The relief valve 30 may also include apiston 108, a valve element 110, and a biasing element 112. The valvebody 100 may also define a chamber 120. In one embodiment, the chamber120 may be generally cylindrical in shape. The piston 106 may include afirst end 122 and a second end 124, and may be sized to translate in alinear direction within the chamber 120 of the valve body 100. FIG. 2illustrates the valve 30 in a closed position, and FIG. 3 illustratesthe valve 30 in an open position. Specifically, the piston 120 maytranslate or move up and down within the chamber 120 of the valve body100 between the closed position and the open position. Although FIG. 2-3describe the chamber 120 as an integral part of the valve body 100(i.e., the chamber 120 and the valve body 100 are a single, unitarypart), it is to be understood that the chamber 120 may also be aseparate piece mounted to the relief valve 30 as well.

In the non-limiting embodiment as shown, the valve element 110 is apoppet-style valve including a valve stem 130. The valve stem 130includes a first end 132 and a second end 134. The first end 132 of thevalve stem 130 may be connected to the second end 124 of the piston 108,and a head 138 of the valve element 110 may be positioned at the secondend 134 of the valve stem 130. Referring to FIG. 2, when the reliefvalve 30 is in the closed position, the head 138 of the valve element110 may be used to generally seal or block off the outlet port 104.Therefore, the head 138 of the valve element 110 may generally block orprevent a fluid from flowing from the inlet port 102 to the outlet port104. As used herein, a fluid may include any liquid, colloid, gas,plasma, or combination thereof.

When a vacuum is applied to the pressurized chamber 106 of the reliefvalve 30, the piston 108 may move in an upwards direction and into theopen position as shown in FIG. 3. When the relief valve 30 is in theopen position, the head 138 of the valve element 110 may be moved awayand no longer blocks or seals off the outlet port 104. Thus, a fluid mayflow through from the inlet port 102 to the outlet port 104 of therelief valve 30 without any substantial obstruction or blockage by thehead 138 of the valve element 110 when the relief valve 30 is in theopen position.

Turning back to FIG. 2, the biasing element 112 may include a first end140 and a second end 142. The first end 140 of the biasing element 112may abut against the first end 122 of the piston 108. The second end 142of the biasing element 112 may abut against a cap 146 of the reliefvalve 30. The biasing element 112 may exert a biasing force against thefirst end 122 of the piston 106. Specifically, the biasing force may beexerted in a downwards direction, and towards the outlet port 104 of therelief valve 30. The biasing force may be used to prevent the piston 108from translating within the chamber 120 of the relief valve 30 and intothe open position due to high boost pressure in the turbo system 10(FIG. 1). In one exemplary embodiment, the biasing element may be acompression spring.

Continuing to refer to FIG. 2, the cap 146 may be affixed or otherwiseattached to the valve body 100 of the relief valve 30. The cap 146 maydefine an opening 150. The opening 150 of the cap 146 may be used tofluidly connect the evacuator 88 with the pressurized chamber 106 of therelief valve 30. The pressurized chamber 106 may be defined by the cap146, a portion of the chamber 120, and the first end 122 of the piston108. The piston 108 translates within the chamber 120 upwards andtowards the cap 146 when a summation of forces acting on the piston 108by the biasing element 112 and a difference in pressure acting on thefirst end 122 and the second end 124 of the piston 108 is greater that aforce applied to the head 138 of the valve element 110 due a pressuredifferential between the inlet port 102 to the outlet port 104 of therelief valve 30. The control valve 38 may normally be in a closedposition, thereby preventing the compressed air from the storage tank 86(FIG. 1) from flowing through the evacuator 88. However, when thecontrol valve 38 is opened, compressed air located within the storagetank 86 may flow through the evacuator 88. The flow of compressed orhigh pressure air through the evacuator 88 may create a vacuum. Thevacuum generated by the evacuator 88 may be communicated to thepressurized chamber 106 of the relief valve 30. When vacuum is appliedto the pressurized chamber 106 of the relief valve 30, this reduces thepressure located within the pressurized chamber 106. The reduction inpressure within the pressurized chamber 106 creates a force that issufficient to overcome the downwards biasing force exerted by thebiasing element 112. This in turn urges the piston 108 upwardly withinthe chamber 120 of the valve body 100, and the relief valve 30 is now inthe open position as seen in FIG. 3.

Referring generally to FIGS. 1-3, if the internal combustion engine 12is either not operating or has initially started, the controller 92 maysend a control signal to the control valve 38 to remain in the closedposition, thereby blocking the compressed air from the storage tank 86(FIG. 1) to the evacuator 88. The controller 92 monitors variousoperating parameters of the internal combustion engine 12 and the turbosystem 10 to determine if the relief valve 30 needs to be opened. Thecontroller 92 may send a control signal to actuate the control valve 32into the open position, thereby allowing the compressed air locatedwithin the storage tank 86 to flow through the evacuator 88 and create avacuum. As explained above, the vacuum may be used to actuate the reliefvalve 30 into the open position as seen in FIG. 3.

Referring to FIGS. 2-4, the evacuator 88 creates a vacuum provided tothe pressurized chamber 106 of the relief valve 30 by the flow of highpressure air from the storage tank 86 through a passageway 160. Thepassageway 160 of the evacuator 88 may generally extend the length ofthe evacuator 88, and is configured to create the Venturi effect. Theevacuator 88 may also include a motive or high pressure port 162 that isin fluid communication with the high pressure air from the storage tank86 (FIG. 1), a suction port 164 which is connected to the pressurizedchamber 106 of the relief valve 30, and an evacuator outlet or lowpressure port 166, which is connected to the noise attenuator 89.

Referring to FIG. 4, the evacuator 88 may be generally “T-shaped” anddefines the passageway 160 along a central axis A-A. The passageway 160may include a first tapering portion or motive cone 172 coupled to asecond tapering portion or discharge cone 174. In the embodiment asshown, the first tapering portion 172 includes a tapered convergingprofile, and the second tapered portion 174 includes a divergingprofile. The first tapering portion 172 and the second tapering portion174 may be aligned end to end, where a motive outlet end 176 of themotive cone 172 faces a discharge inlet 178 of the discharge cone 174 todefine a Venturi gap 180 therebetween. The Venturi gap 180 as usedherein means the lineal distance between the motive outlet end 176 andthe discharge inlet 178. Some exemplary configurations for the evacuator88 are presented in FIGS. 4-6 of co-pending U.S. patent application Ser.No. 14/294,727, filed on Jun. 3, 2014, which is incorporated byreference herein in its entirety.

Referring to FIG. 1-4, during operation when the control valve 38 isopened, compressed air located within the storage tank 86 may enter thehigh pressure port 162 of the evacuator 88. As the compressed air flowsthrough the high pressure port 162, which includes a converging profilethat decreases in area, the velocity of the compressed air may increase.This is because the laws of fluid mechanics state that the staticpressure decreases as fluid velocity increases. The motive outlet end176 of the motive cone 172 may abut the Venturi gap 180. The Venturi gap180 may be fluidly connected to the suction port 164, which exposes thecompressed air in the suction port 164 to the same low static pressurethat exists in the air that passes between the high pressure port 162and the low pressure port 166 and creates the vacuum that is provided tothe pressurized chamber 106 of the relief valve 30.

In the embodiments as described above and shown in FIGS. 2-3, the reliefvalve 30 operates as an open/close valve that is either fully open orfully closed. However, in the alternative embodiment as shown in FIG. 5,a variable relief valve 230 may be provided. FIG. 5 is a schematicdiagram of the relief valve 30, the control valve 38, the evacuator 88,the storage tank 86, the controller 92, a position sensor 202, and avent valve 204. The position sensor 202 and the vent valve 204 are insignal communication with the controller 92. The position sensor 202 maybe provided to detect the position of the piston 108 within the chamber120 of the valve body 100 as the piston 108 is actuated between theclosed position and the open position. In another embodiment, the ventvalve 204 may not be connected to the controller 92, and instead is asimple restriction connected to atmosphere.

The position sensor 202 may be any device that permits positionmeasurement. In one embodiment, the position sensor 202 is a relativeposition sensor (a displacement sensor) based on movement of the piston108 within the chamber 120 of the valve body 100. The position sensor202 may be a capacitive transducer, an eddy-current sensor, a gratingsensor, a Hall-effect sensor, an inductive non-contact position sensor,a laser Doppler Vibrometer (optical), a linear variable differentialtransformer (LVDT), a multi-axis displacement transducer, a photodiodearray, a piezo-electric transducer (piezo-electric), a potentiometer, aproximity sensor (optical), a seismic displacement pick-up, a stringpotentiometer (also known as string pot., string encoder, cable positiontransducer), or a combination thereof.

In one embodiment, the position sensor 202 is a Hall effect sensorcomprising a chip/Hall effect position sensor 210 that sensors thedisplacement of a magnet 212. The magnet 212 may be connected to thepiston 120 for translation therewith. Specifically, the magnet 212 maybe mounted to or placed within the piston 108. The chip/Hall effectposition sensor 210 may be positioned within the valve body 100 insufficient proximity to sense the movement of the magnet 212 locatedwithin the piston 108, and determine the specific position of the piston108 within the chamber 120 of the valve body 100. In the embodiment asshown in FIG. 5, the chip/Hall effect position sensor 210 is orientedhorizontally in a position above the magnet 212 (i.e., axial relative tothe magnet 212). In another embodiment, the chip/Hall effect positionsensor 210 may be oriented vertically in a position radially outwardaway from the magnet 212.

The vent valve 204 may be in fluid communication with the pressurizedchamber 106 of the valve body 100, and connects the pressurized chamber106 to the atmosphere. The vent valve 204 may be used to vent off ordecrease the amount of vacuum in the pressurized chamber 106.Specifically, when the control valve 38 is opened, compressed airlocated within the storage tank 86 may flow through the evacuator 88 tocreate the vacuum. The vent valve 204 may be used to vary the amount ofvacuum located in the pressurized chamber 106. Varying the amount ofvacuum in the pressurized chamber 106 may control the position of thepiston 108 within the chamber 120 of the valve body 100. In other words,the piston 108 may be positioned in any one of a plurality of partiallyopened positions based on a predetermined amount of vacuum applied tothe pressurized chamber 106.

In one embodiment, the amount of vacuum applied to the pressurizedchamber 106 may be varied using pulse width modulation (PWM) control.Specifically, the controller 92 may send a current signal to the ventvalve 204. The current signal may be used to modulate the vent valve 204off and on. A duty cycle of the current signal is varied in order toposition the piston 108 in one of the partially opened positions withinthe chamber 120 of the valve body 100.

FIGS. 6-9 are an exemplary alternative illustration of a variable reliefvalve 310. Specifically, FIGS. 6 and 7 are an illustration of the valve310 in the closed position, where a piston 312 blocks flow between aninlet 314 and an outlet 316 of the valve 310. FIG. 8 is an illustrationof the valve 310 in a partially opened position, and FIG. 9 is anillustration of the valve 310 in a fully opened position. In theembodiments as illustrated in FIGS. 2-5, a poppet valve may be used toblock flow. In contrast, the valve 310 uses the piston 312 to block theflow of fluid between the inlet 314 and the outlet 316. Referring toFIG. 6, the valve 310 may include the piston 312, an inner housing 320,an outer housing 322, a bushing 324, a biasing element 326, a positionsensor 328, and a control port 330. The control port 330 may be fluidlyconnected to the suction port 164 of the evacuator 88 (shown in FIG. 4).The valve 310 may be seated within a chamber 332 housing 340.

The inner housing 320 and the outer housing 322 may cooperate with oneanother to form a void or space therebetween. The void between the innerhousing 320 and the outer housing 322 may define a pressurized chamber342. In the embodiment as shown, a body 344 of the piston 312 may alsodefine a void or chamber 346 that is fluidly connected to the voidlocated between the inner housing 320 and the outer housing 322.Moreover, the inner housing 320 may define a passageway 346 and an innerchamber 350. The passageway 346 may be used to fluidly connect the innerchamber 350 of the inner housing 320 with the pressurized chamber 342 ofthe valve 310. In the embodiment as illustrated, the inner chamber 350of the inner housing 320 may be generally cylindrical, and is configuredto receive a corresponding protrusion 352 of the piston 312. Theprotrusion 352 of the piston 312 may also be generally cylindrical. Thebushing 324 may be placed between an inner surface 360 of the innerchamber 350 of the inner housing 320 and an outer surface 362 of theprotrusion 352 of the piston 312. The protrusion 352 of the piston 312may be hollow to define a generally cylindrical void or cavity 364therein.

In the embodiment as shown, the void 364 of the piston 312 may receive amagnet 366 of the position sensor 328. A chip/Hall effect positionsensor 368 may be placed along an upper surface 369 of the inner housing322. The position sensor 368 may be used to sense the displacement ofthe magnet 366 as the piston 320 translates upwardly and downwardlywithin the housing 340 with respect to the upper surface 369 of theinner housing 322.

The control port 330 may be in fluid communication with the pressuredchamber 342 such that vacuum from the evacuator 88 (FIG. 4) may besupplied to the pressurized chamber 342 via the control port 330.Specifically, as vacuum is applied to the pressured chamber 342 of thevalve 310, the piston 312 may translate in an upwards direction withinthe housing 340, and into the partially opened position (shown in FIG.8) or into the fully opened position (shown in FIG. 9).

In the non-limiting embodiment as shown, the biasing member 326 is acoil spring. The biasing element 326 may include a first end 370 and asecond end 372. The first end 370 of the biasing element 372 may beseated against a shoulder 374 defined by the inner housing 320.Likewise, the second end 372 of the biasing element 326 may be seatedagainst a shoulder 376 defined by the piston 312. The biasing element326 may exert a biasing force against a first end 378 of the piston 312.Specifically, the biasing force may be exerted in a downwards direction,and towards the inlet port 314 of the relief valve 310. Similar to theembodiment as discussed above and illustrated in FIGS. 2-5, the biasingforce may be used to prevent the piston 312 from translating within thehousing 340 and into the open position due to high boost pressures inthe turbo system 10 (FIG. 1).

A first seal 380 may be received by an annular recess 382 located alongan outer surface 384 of the piston 312. Specifically, the first seal 380may be located at the first end 378 of the piston 312. The first seal380 may be, for example, an O-ring. The first seal 380 may abut againstan opening 384 of the inlet 314 of the valve 310. The first seal 380 maybe used to provide a generally fluid-tight seal between the piston 312and the housing 340 when the valve 310 is in the closed position. Asecond seal 390 may be received by an annular recess 392 located alongthe outer surface 384 of the piston 312. The second seal 390 may also bean O-ring, and is located at a second end 394 of the piston 312. Thesecond seal 390 is configured to provide sealing between the piston 312and an inner surface 396 of the outer housing 320 as the piston 312translates within the housing 340.

Referring generally to the figures, the disclosed evacuator may be usedto provide vacuum to a relief valve. Some other types of systems thatare currently available may use a vacuum pump to supply the vacuumneeded to actuate a relief valve. The vacuum pump may be driven by anelectric motor or by the crankshaft of an internal combustion engine.The evacuator provides a simpler, low-cost alternative for supplyingvacuum to a relief valve.

The embodiments of this invention shown in the drawings and describedabove are exemplary of numerous embodiments that may be made within thescope of the appended claims. It is contemplated that numerous otherconfigurations of the disclosure may be created taking advantage of thedisclosed approach. In short, it is the applicants' intention that thescope of the patent issuing herefrom will be limited only by the scopeof the appended claims.

What is claimed is:
 1. A valve assembly, comprising: an evacuator havinga suction port that selectively applies a vacuum; a variable reliefvalve having at least an open position and a closed position, thevariable relief valve comprising: an inlet and an outlet; a pistonmoveable within a pressurized chamber, the piston including a first endand a second end; a pressurized chamber fluidly connected to the suctionport of the evacuator, the pressurized chamber defined in part by thefirst end of the piston, and wherein the piston translates within thepressurized chamber towards the open position if vacuum is applied tothe pressurized chamber; and a vent valve fluidly connected to thepressurized chamber, wherein the vent valve varies an amount of vacuumin the pressurized chamber to control a position of the piston withinthe pressurized chamber.
 2. The valve assembly of claim 1, comprising avalve element connected to the second end of the piston, wherein thevalve element includes a head that selectively blocks fluid from flowingfrom the inlet to the outlet.
 3. The valve assembly of claim 1, whereinthe variable relief valve is a poppet-style valve including a valve stemhaving a first end and a second end, and wherein the first end of thevalve stem is connected to the send end of the piston and the second endof the valve stem may include a head.
 4. The valve assembly of claim 3,wherein the head of the valve stem generally seals the outlet of thevariable relief valve if the variable relief valve is in the closedposition.
 5. The valve assembly of claim 1, comprising a biasing elementhaving a first end and a second end, wherein the first end of thebiasing element abuts against a cap of the variable relief valve and thesecond end of the biasing element exerts a biasing force against thefirst end of the piston.
 6. The valve assembly of claim 5, wherein thebiasing force is exerted towards the outlet of the variable reliefvalve.
 7. The valve assembly of claim 1, wherein the evacuator defines aconverging motive section, a diverging discharge section, the suctionport, and a Venturi gap, wherein the Venturi gap is fluidly connected tothe suction port.
 8. The valve assembly of claim 1, comprising aposition sensor for detecting a position of the piston within thepressurized chamber.
 9. The valve assembly of claim 1, wherein thepiston blocks flow of fluid between the inlet and the outlet of thevariable relief valve.
 10. The valve assembly of claim 9, comprising acontrol port that fluidly connects the suction port of the evacuatorwith the pressurized chamber.
 11. The valve assembly of claim 9, whereinthe variable relief valve includes an inner housing and an outer housingthat corporate with one another to create a space therebetween thatdefines the pressurized chamber.
 12. The valve assembly of claim 11,wherein the piston includes a body that defines a piston chamber, andwherein the piston chamber is fluidly connected to the space between theinner housing and the outer housing.
 13. A system including anexhaust-driven turbo charger, comprising: a storage tank containingcompressed air; a control valve selectively opened to allow for thecompressed air within the storage tank to flow therethrough; anevacuator fluidly connected to the control valve and a compressor inletof the exhaust-driven turbo charger, wherein the evacuator includes asuction port that applies a vacuum if the control valve is opened; avariable relief valve having at least an open position and a closedposition, the variable relief valve fluidly connected to the evacuator,wherein the variable relief valve is actuated into the open position ifthe vacuum is applies by the evacuator, the variable relief valvecomprising: an inlet and an outlet; a piston moveable within apressurized chamber, the piston including a first end and a second end;a pressurized chamber fluidly connected to the suction port of theevacuator, the pressurized chamber defined in part by the first end ofthe piston, and wherein the piston translates within the pressurizedchamber towards the open position if vacuum is applied to thepressurized chamber; and a vent valve fluidly connected to thepressurized chamber of the variable relief valve, wherein the vent valvevaries an amount of vacuum in the pressurized chamber to control aposition of the piston within the pressurized chamber.
 14. The system ofclaim 13, wherein the variable relief valve is a compressorrecirculation valve that is fluidly connected to and vents thecompressed air back into the compressor inlet of the exhaust-driventurbo charger.
 15. The system of claim 13, wherein the variable reliefvalve is a blow-off valve that vents the compressed air into atmosphere.16. The system of claim 13, wherein the control valve is a solenoidvalve.
 17. The system of claim 13, wherein the control valve is in anormally closed position to prevent the compressed air from the storagetank from flowing through the evacuator.